Sunday, April 8, 2012

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Pitch: it is a sensation experienced by a listener. It is a subjective term which cannot be measured quantitatively. The pitch of a sound depends upon the frequency of vibration air. If the frequency of a sound is high, its pitch is high and if the frequency of sound is low. The high pitch sound is shrill and the low pitch sound is grave or flat. The voice produced by ladies and children is shrill. Similarly, the sound produced by a mosquito is of high pitch and therefore shrill. However, the voice of an old man is hoarse or flat because of low pitch.

Loudness: loudness is a subjective sensation that depends on listener. It depends on the intensity and also on the sensitiveness of the listener’s ear. Intensity of sound is the sound energy flowing per second per unit area perpendicular to the direction of travel of the sound. Loudness is the characteristics of a musical sound by which a loud sound can be distinguished from a faint sound even though the two have the same pitch. It is however, subjective and cannot be measured quantitatively. If the intensity of sound near the ear is high, the loudness will be high. Loudness (or intensity) depends upon the following factors:

a.Amplitude of the vibration of source, greater is the amplitude of the vibration of source, larger is the intensity and hence, loudness of the sound also.

b.Motion of the medium, if the wind is blowing in the direction of propagation of sound, the loudness of the sound increases and on the other hand, if the wind is blowing in the opposite direction of travel of sound, the loudness decreases.

c.Presence of the other bodies; the loudness of sound is increased due to presence of other bodies near the source of sound.

d.Surface area of vibrating body. The greater the surface area of vibrating body, the larger is the loudness of the sound. For example, the sound from a large drum or a speaker is higher than that from a small surface area.

e.Frequency of sound. The loudness of a vibrating body is directly proportional to the frequency of the vibrating body.

Quality or timber: it is a measure of complexity of sound which enables us to distinguish between two sounds of the same pitch and loudness produced by two different sources. It depends upon waveform of the sound. So, we can distinguish sounds from two different instruments even though they have the same tone and loudness. This is due to the different quality of sound produced by two instruments. The note produced by an instrument does not contain a single frequency but consists of a fundamental note (which usually predominates) and overtones with smaller intensity. The fundamental note has the lowest frequency and the overtones have frequencies multiplies of fundamental frequency. Thus, the number and intensities of the overtones determine and quality of a sound.

This post was written by: Pooja

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